1. Field of the Invention
The present invention relates generally to equipment used in the printing industry, and more particularly is a paper turner for a work and turn operation.
2. Description of the Prior Art
The printing industry requires a good deal of high cost capital equipment. Much of the cost of a given printing job is due to the expense of the printing presses. A simple, low end press costs $100,000, and a high end, multi-color press costs millions of dollars. Multi-color presses typically require more than one press operatorxe2x80x94a head press man and at least one press helper. The head press man sets up the color and the registration, and the press helper feeds the paper. If a particular shop cannot afford the expense of the press helper, then the head press man does both the set up work and the paper feeding. This situation significantly slows the pace of production.
Printing presses are also distinguished by whether they print on only one side of the paper on a given run (a straight press), or whether they print on both sides of the paper simultaneously (a perfecting press). The distribution of these machines in the printing industry is roughly 90%/10%, with the straight presses being the far more common machine. This means that the majority of printing work is done on a straight press, printing on one side at a time, even though most printing jobs require printing on two sides.
Therefore, most of the time a xe2x80x9cwork and turnxe2x80x9d operation is required. That is, the first side is printed, then the paper is flipped over, and the second side is printed by running the paper through the same press a second time. The turning operation is generally accomplished manually, by either the head press man or the press helper. The turner must take the stack of paper printed on one side back to the feeding area at the rear of the press, turn the paper, usually in stacks of two to three inches, and feed the paper back into the press. This is clearly a time consuming operation, and if there is only, a single press operator, the operator has to monitor the colors and the registration-while feeding the press. This arrangement slows the operation and can adversely affect the print quality.
The prior art automation solution for the work and turn operation is a hydraulic turning machine. This current art machine clamps the paper to be turned tightly on both the top and bottom of the paper, lifts the paper, and turns it. This is a costly solution to the work and turn problem, in that the automatic turning machines cost from $17,000 to $30,000. Moreover, the automatic turning machines can create yet another problem. The pressure used by the machines to secure the paper can offset the print if the printed material is not allowed to dry before the turning operation. If you turn the printed paper too soon, the work is destroyed. If you wait for the ink to dry, delay is introduced into the printing process.
Accordingly, it is an object of the present invention to provide a method of automating the work and turn operation.
It is a further object of the present invention to provide a turning mechanism that allows the turn operation to be completed immediately after the first printing run without a likelihood of offsetting print, even though the paper is turned before it has dried.
It is a still further object of the present invention to provide a turning machine that is relatively inexpensive, and that is easy to use.
The present invention is a load turning device specifically designed to turn paper in a work and turn printing process. The paper turner comprises a pair of slides mounted on a pair of parallel tracks supported by bracing elements. To turn the paper stack, the paper turner is positioned so that a first slide is under the pallet on which the paper stack rests. The second slide is lowered to rest on top of the paper stack, and the slides are locked in position relative to each other.
The paper turner is then turned, using wheels and pivot rests affixed to the frame to support the weight, until the stack is in a horizontal position. The slides and the paper stack are then moved to the opposite end of the tracks. The frame is again rotated until it is in a vertical orientation, rotated 180xc2x0 from its original position. The printed sides of the paper are now facing downward, and the paper is ready to be loaded into the printing press.
An advantage of the present invention is that it allows a single operator to efficiently perform a work and turn operation.
Another advantage of the present invention is that it does not require heavy pressure on the freshly printed paper, so that the print quality is not jeopardized.
A still further advantage of the present invention is that it greatly reduces the time required for a double-sided printing job on a straight press.